In producing a synthetic resinous container, such as a polyethylene bottle or a container of other plastic materials, a semi-fluid tubular parison either of one or multiple layers of resin is fed from an overhead extruding head downwardly between two halves of a mold which are brought into alignment on opposite sides of the parison. Upon closure of the molds about the parison it is then cut free of the mold. During closure of the mold halves about the parison, the parison is still in motion downwardiy from the extruder and the mold being closed thereabout must be moved downwardly with the parison to avoid critical extruder operational inefficiencies otherwise experienced by interruption of parison flow. The closed mold is thereupon withdrawn laterally from the extruder station for blowing thus allowing the end of the parison to continue its downward flow from the extruder outlet above ready for receipt by another mold. In the withdrawn lateral position of the mold, the mold halves are opened and the blown bottle is released therefrom.
When labels are supplied to the mold, usually one to each mold half, means for inserting and applying the labels to the walls of the open halves is provided which must act quickly before the two halves close about the parison otherwise impart a time delay in the molding cycle. In the usual shuttle machine for producing containers in this manner, two complete sets of moveable mold halves are provided on opposite sides of the path of flow of the parison. First one open set of mold halves is moved into place from its lateral position into alignment on opposite sides of the parison and then closed about the parison to form the desired container. The parison is then cut free of the mold and the closed mold is withdrawn to a lateral position for blowing to conform to the mold cavity and removal of the container. Simultaneously the second open mold set is brought into place on opposite sides of the parison for closure to form another container. The second mold set is thereupon withdrawn for blowing and removal of a container and return to its beginning position. This process cycle is repeated continuously, alternating the mold sets between one side and the other of the parison thereby allowing the parison to flow continuously from the extruder without interruption.
since the mold halves are closed about the parison while the parison is in downward motion, the mold set must be moved downwardly at a rate corresponding to the rate of motion of the parison to prevent flow interruption. A means is therefore provided to move the closed mold downwardly with the parison during the momentary confinement of the parison in the mold before and during cutoff and withdrawal to a lateral position where the container is removed upon opening the mold halves.
To allow the downward movement of the mold with the parison the mold halves are usually arranged first to be brought up to an upper level position on opposite sides of the parison path and as the end of the downward moving parison reaches the bottom of the mold halves, closure of the mold is already initiated and occurs quickly to allow cutoff of the parison above and lateral withdrawal of the closed mold to avoid interruption of the parison flow. The second set of mold halves on the opposite side of the parison thereupon comes into position in the upper region to start the cycle of container formation over again.
Since it is important for efficiency of operation that the parison flow from the extruder not be interrupted, the time available is quite limited for insertion of labels on the walls of the mold halves without incurring a delay in the production cycle. This requires rapid action by the mechanism for inserting the labels on the walls of the mold halves. That is, the label inserter must get in between the mold halves quickly while they are open and get out quickly before the space between the closing mold halves becomes too small for the mechanism to be safely present therein.
The shuttle type machine most commonly used in the container manufacturing industry has two confronting mold supporting platens extending laterally outward from the machine, one for each mold half. The inside platen closest to the machine is hydraulically driven directly toward the outside platen while the outside platen is drawn to the other in cooperation therewith through a rack and pinion gear assembly to drive the two together or away from each other. The outside moveable platen is supported in cantilevered fashion by two heavy support rods, one in an upper position on one side of the mold halves and the other in a diagonally opposite low position below the level of the two mold halves. Accordingly beside being capable of acting at a high speed, the mechanism must be compact enough to fit and be able to accommodate its operation to those of the molding operations as well as the position of components of the molding apparatus throughout the product molding cycle.
In light of the foregoing it is a principal object of the present invention to provide label insertion equipment and a method for supplying labels to mold cavities of shuttle type in-mold labeling apparatus with minimum or no delay in the molding cycle for producing the labeled synthetic resin products.
It is another important object of the invention to provide label insertion equipment for inserting labels into molds of in-mold label production apparatus adaptable to the space confines surrounding such production apparatus.
It is still another object of the invention to provide label insertion equipment and a method for inserting labels into molds of in-mold label production apparatus flexibly adaptable to the time cycle of production as well as the involved motion dynamics of the labeled product production apparatus.